The teenager published images of his injuries on Facebook and spoke at length of how he had been the victim of homophobia.

He wrote on Facebook: “What was their motive? because of my f**king sexuality. something that doesn’t concern ANYONE else minus me and the person I fall for, either man or woman. A sex life is private and has nothing to do with no one, needless to say it’s absolutely disgraceful to violently attack someone because of who they are. My confidence has gone; I’m utterly embarrassed to be seen in public, the only reason I am putting this picture up is because I want you to see me as an example. An example why homophobia is wrong and it’s disgusting that it’s still around in 2014.”

The police initially believed Mr Kennedy’s accounts of the events, with Detective Sergeant Martin Pearson saying on Wednesday 5 March: “This was a particularly nasty assault, aggravated by the homophobic comments which were made before Richard was attacked.

“Whilst we are keeping an open mind, we do believe he may have been targeted because he is gay.”

Mr Fry’s intervention generated increased publicity for the investigation, with the story being re-tweeted hundreds of times.

But today Lancashire Constabulary released a statement saying detectives have now established that no offences have been committed – and that Mr Kennedy’s injuries were sustained as a result of a fall.

Detective Inspector Paddy O’Neill said: “We managed to recover some CCTV footage which shows the injured party falling face-first onto the pavement. We have showed him the CCTV and he now accepts his injuries were caused during the fall.

“Having had oversight of the investigation since its inception and taking into account the full circumstances, I accept his report was made in good faith.

“The investigation into this matter is indicative of the lengths we will go to when investigating reports of violent crime in the city. We believe assaults, and hate crime assaults in particular, are under-reported in the city for many reasons.

“Lancashire Constabulary is committed to ensuring that all forms of hate crime are investigated thoroughly; any reports made to the police will be taken seriously. I am conscious that the initial reports into this incident will have been very upsetting for a number of people, and Preston city centre was portrayed in a very negative light. Thankfully, there was no homophobic assault or any other assault on this occasion.”